Chapter 4 Computer Hardware - PowerPoint PPT Presentation

About This Presentation
Title:

Chapter 4 Computer Hardware

Description:

Information Technology in Theory By Pelin Aksoy and Laura DeNardis Chapter 4 Computer Hardware * Cooling System A significant amount of heat is generated by the many ... – PowerPoint PPT presentation

Number of Views:971
Avg rating:3.0/5.0
Slides: 93
Provided by: Cours63
Learn more at: http://www.cs.ucf.edu
Category:

less

Transcript and Presenter's Notes

Title: Chapter 4 Computer Hardware


1
Chapter 4Computer Hardware
  • Information Technology in Theory
  • By Pelin Aksoy and Laura DeNardis

2
Objectives
  • Identify some important historical milestones in
    the development of computers
  • Understand logic gates and how computers use them
    to process information
  • Identify the fundamental components of a computer
  • Understand how computer performance depends on
    factors such as processor speed, chip set, bus
    width, bus speed, number of CPUs, and instruction
    set

3
Objectives (continued)
  • Examine future trends in computing and societal
    issues related to these advances
  • Understand the physical principles of data
    storage and the difference between mechanical,
    magnetic, optical, and electronic storage

4
A Brief History of Computers
  • Computing devices trace back at least to the
    Abacus
  • Mechanical calculation tools in the 1600s
    included William Oughtreds slide rule,
    BlaisePascals arithmetic machine, and Leibnizs
    step reckoner
  • Calculation tools of the 1800s included Charles
    Babbages Difference and Analytical engines
  • Augusta Ada Byron, the Countess of Lovelace,
    worked with Babbage in programming the analytical
    engine
  • Herman Hollerith developed the tabulating machine
    to tabulate the 1890 US census data using punch
    cards

5
A Brief History of Computers (continued)
  • The punch card concept is attributed to Joseph
    Marie Jacquard
  • The 1940s spurred big advancements in computing
  • John Vincent Atanasoff and Clifford Berry at the
    Iowa State College built the ABC
  • Konrad Zuse built the Z3
  • Howard Aiken built the Mark I, which was
    programmed by Grace Murray Hopper
  • British scientists built the Colossus
  • John Mauchly and J. Presper Eckert built the
    ENIAC

6
A Brief History of Computers (continued)
  • The transistor and integrated circuit enable
    smaller computers compared to vacuum tubes
  • Popular Electronics ran a feature story about a
    home do-it-yourself computer kit called the
    Altair
  • Radio Shack began to sell the TRS-80 home
    computer, and Apple Computer Inc. introduced its
    own line of home computers
  • These advances, and the introduction of IBMs
    personal computer (PC) in 1981, contributed to
    the explosion of computers in all facets of
    modern life

7
A Brief History of Computers (continued)
  • A variety of social and economic factors, along
    with advances in microprocessors and distributed
    networks, led to the introduction of mobile,
    wireless, and handheld computers

8
Digital Logic
  • A computer has one or more main chips called the
    microprocessor, which performs most of the
    processing, and several other supporting chips
  • Integrated circuits such as microprocessors are
    built by combining transistors together to create
    logic gates
  • These basic building blocks can be combined to
    create successively larger building blocks, which
    may subsequently be combined to create complex
    circuitry and packaged with other components
    within a carrier to create integrated circuits
    such as microprocessors

9
Digital Logic (continued)
10
Digital Logic (continued)
  • Integrated circuits are built using the following
    types of logic gates
  • The difference between these logic gates is
    essentially the way the transistors within them
    are connected to each other
  • NOT gate (inverter)
  • AND gate
  • NAND (not AND) gate
  • OR gate
  • NOR (not OR) gate
  • Exclusive OR (XOR) gate
  • XNOR (exclusive NOR) gate

11
Digital Logic (continued)
12
Digital Logic (continued)
13
Digital Logic (continued)
Combining log gates to create a 1-bit binary adder
14
Digital Logic (continued)
15
Fundamental Components of a Computer
16
Fundamental Components of a Computer (continued)
  • Computer hardware is any physical device
    associated with a computer, such as a keyboard or
    monitor
  • Besides the instructions that users issue through
    input hardware devices, computers also receive
    instructions via the software stored in its
    memory
  • Software is traditionally defined as a series of
    instructions written by computer programmers in a
    language that people can understand and that the
    computer can translate into binary
  • The computer must interpret and then execute each
    software instruction, again through the use of
    its transistors

17
Input/Output Devices
  • Input and output devices are hardware components
    that interface a computer to the outside world
  • Examples of input devices include
  • Mice
  • Trackballs
  • Microphones
  • Web cams
  • Styluses
  • Touch pads
  • Pointing sticks
  • Joysticks
  • Scanners

18
Input/Output Devices (continued)
  • Examples of output devices include
  • Printers
  • Plotters
  • Speakers
  • Projectors
  • Some I/O devices, such as keyboards and monitors,
    are integral parts of computers
  • However, note that not all computers have input
    and output devices connected to them
  • For example, some computers can interface to a
    user over a network and do not need their own I/O
    equipment

19
Central Processing Unit
  • The most crucial component of any computer is a
    chip called the microprocessor or central
    processing unit (CPU)
  • The microprocessor controls the major
    functionality of the computer and is often called
    the brains of the computer
  • The microprocessors many tasks include fetching
    a wealth of software instructions, interpreting
    and executing these instructions, and storing and
    outputting results

20
Central Processing Unit (continued)
21
Central Processing Unit (continued)
  • Key component of the CPU is the control unit,
    where instructions are interpreted and control
    signals are generated
  • Based on the result of the interpretation, the
    control unit supplies crucial control signals to
    other parts of the computer
  • If the instruction involves the addition of two
    numbers, then the control unit issues control
    signals to a unit called the ALU, which is
    responsible for arithmetic and logical operations

22
Central Processing Unit (continued)
  • The registers within the CPU are small areas for
    temporarily storing information, such as
    instructions that are supplied to the control
    unit and the results of addition and comparison
    operations implemented by the ALU
  • Software instructions that the CPU interprets and
    data that it processes are fetched from a module
    called main memory that resides outside the CPU
  • Unlike main memory, cache memory is internal to
    the CPU

23
Central Processing Unit (continued)
  • Cache memory holds frequently used instructions
    and data
  • Because some software instructions and data are
    needed more often than others by the CPU, they
    can be stored inside the cache memory and
    retrieved when necessary instead of having to be
    fetched from the distant main memory every time
    they are needed
  • Saving frequently used instructions and data in
    close proximity saves considerable time and
    energy

24
Main Memory
  • Main memory of a computer consists of two types
    of memory random access memory (RAM) and
    read-only memory (ROM)
  • RAM is much more prominent it retains its
    contents as long as power is supplied to the
    computer and loses its contents when the power is
    switched off
  • RAM is also called temporary memory or volatile
    memory
  • ROM, on the other hand, retains its contents even
    after power to the computer

25
Main Memory (continued)
  • Essentially, two types of RAM are used to store
    information as long as power is supplied to the
    computer static RAM (SRAM) and dynamic RAM
    (DRAM)
  • The contents of dynamic RAM must be refreshed
    several times per second, because the electrical
    charges representing the bits of DRAM leak out
    and must be replenished
  • There is no need to refresh the contents of SRAM
  • DRAMs include transistors and other electronic
    components called capacitors that store
    electricity, whereas SRAMs are based on
    transistors

26
Main Memory (continued)
  • Although capacitors can store electricity, they
    cannot do so indefinitely
  • Electricity eventually leaks out of them, which
    is why it is necessary to refresh the contents of
    DRAM
  • Memory chips that correspond to the main memory
    are mostly DRAM
  • Cache memory within the CPU is typically SRAM
  • Due to fundamental differences in how the two
    types of RAM are constructed, they differ in
    speed, size, and cost

27
Main Memory (continued)
  • It is faster to save and retrieve the contents of
    SRAM, but SRAM is also more expensive and larger
    than DRAM
  • Because cache memory has to be fast, it is better
    to use SRAM to build cache memory
  • DRAM is used within the main memory because it is
    the main holding area of the computer and must
    have a large holding capacity
  • Main memory also must be cheap to minimize the
    cost of the computer

28
Main Memory (continued)
  • RAM chips retain ones and zeros that correspond
    to instructions and data within small areas
    called cells
  • Each RAM cell can hold one bit of information,
    regardless of whether it is DRAM or SRAM
  • Cells within RAM chips are arranged in rows and
    columns
  • Saving information to RAM is referred to as
    writing to RAM, and retrieving RAM contents is
    called reading the RAM
  • Information is written to and read from the RAM
    by addressing the RAM cells using addresses

29
Main Memory (continued)
30
Main Memory (continued)
31
Main Memory (continued)
  • Although a major part of the instructions that
    the computer executes are supplied from RAM, the
    computer also relies on some operations based on
    instructions stored in ROM chips
  • ROM chips and RAM chips physically reside at
    different places within a computer, but together
    they constitute the main memory of the computer
  • The BIOS chip is an example of a ROM chip found
    inside a computer

32
Main Memory (continued)
  • The major variations of ROMs have historically
    included the following
  • Programmable ROM (PROM)
  • Erasable programmable ROM (EPROM)
  • Electrically erasable programmable ROM (EEPROM)
  • A device that is similar to EEPROM is flash memory

33
Storage
  • Storage and retrieval of digital information is
    one of the most critical components of an IT
    system
  • Without storage, we would have no Web servers,
    electronic banking, e-mail, or almost any other
    digital application
  • Storage technologies are discussed later in the
    chapter

34
Interconnection System
  • The physical system that connects I/O devices,
    main memory, CPU, storage, and other components
    is called the interconnection system
  • This system is actually a set of wires they are
    often grouped together as a set of parallel wires
    that transfer signals corresponding to data,
    instructions, and control information in an
    arrangement called a parallel bus
  • Some connections do not rely on a set of parallel
    wires
  • Instead, they use a main connection that
    transfers bits one after the other, or serially,
    from one point to another
  • Such connections are called a serial bus

35
Interconnection System (continued)
36
Interconnection System (continued)
  • The number of parallel lines within a parallel
    bus and the transfer speed of bits across each
    line dictate how many overall bits the bus can
    carry
  • The larger the bus width, the quicker the bits
    can reach their destination an example would be
    the delivery of bits from the main memory to the
    CPU

37
Interconnection System (continued)
  • Types of computer buses include the following
  • System busA parallel bus that connects the CPU
    and main memory the system bus is also called
    the front side bus
  • Peripheral Component Interconnect (PCI) bus and
    PCI Express (PCI-E) busThe PCI bus and its newer
    and faster version, PCI-E bus, connect expansion
    cards such as network interface cards and sound
    cards/adapters
  • Accelerated Graphics Port (AGP) busThis bus
    connects expansion cards called graphics
    cards/adapters to the CPU this circuitry
    supports computer graphics capabilities

38
Interconnection System (continued)
  • Expansion cards are connected to the CPU by buses
  • They are attached to the buses by being plugged
    into special components called expansion slots on
    the computers motherboard

39
Factors That Affect Computer Performance
  • Some of the key factors that affect computer
    performance are shown in the following list
  • Word length
  • Bus width and bus speed
  • Memory size and memory access speed
  • Processor speed
  • Instruction set
  • Number of CPUs
  • Chip set

40
Word Length
  • Word length is expressed in terms of bits and
    corresponds to the maximum number of bits of
    information that a computer can process at one
    time
  • The larger the word length is, the faster the
    computer
  • Engineers are constantly striving to design
    computers with larger word lengths to achieve
    high performance

41
Word Length (continued)
42
Bus Width and Bus Speed
  • Another factor that affects performance is the
    bus size, or parallel bus width
  • Like word length, bus size is measured in terms
    of bits
  • A computer with a large bus width can carry more
    bits at a time between computer components, such
    as between main memory and the CPU, making it
    faster than a computer with a small bus width
  • Because the buses carry important instructions,
    data, addresses, and control signals, the speed
    you can gain by using a larger bus width is
    important

43
Bus Width and Bus Speed (continued)
  • The bus size determines how many physical wires
    are constructed within the bus
  • The more wires that designers can incorporate
    within a bus, the larger the bus width becomes,
    meaning that the bus can carry more bits at one
    time
  • Bus speed, which is measured in hertz (Hz), also
    affects computing performance
  • Even if large bus widths can enable large number
    of bits to move between computer components in
    parallel, each bus line must also carry bits as
    quickly as possible

44
Memory Size and Memory Access Speed
  • Computers need large amounts of memory for high
    performance and multitasking
  • Because every program occupies some amount of
    space in RAM, a large amount of RAM is essential
    to operate with multiple programs
  • Furthermore, RAM size significantly affects
    computer speed because information is frequently
    written to and erased from RAM
  • If there is insufficient RAM space, the computer
    must frequently resort to using its hard disk,
    which results in diminished performance

45
Memory Size and Memory Access Speed (continued)
  • Other than RAM, the size of the cache memory
    (expressed in bytes) is also a consideration
  • The more cache memory the CPU has, the better the
    CPU performs
  • The speed at which RAM and cache memory contents
    are written and retrieved helps to determine
    performance
  • The higher the read/write speed, the faster the
    computer is
  • Typical RAM access speeds are on the order of
    nanoseconds (ns), or billionths of a second

46
Processor Speed
  • The on and off switching of transistors within
    the integrated circuits of a computer is managed
    by a central digital electrical signal called a
    clock
  • Computer clock speeds are measured in frequency
    units called hertz
  • Just as multipliers are used in the IT world to
    express large numbers of bits, multipliers are
    used to express large frequency values
  • 1 kHz 1000 Hz
  • 1 MHz 1,000,000 Hz
  • 1 GHz 1,000,000,000 Hz

47
Processor Speed (continued)
  • The higher the clock frequency, the faster the
    computer usually is
  • Typical clock frequencies for modern computers
    range from hundreds of megahertz to a few
    gigahertz

48
Processor Speed (continued)
49
Instruction Set
  • A computers CPU is typically based on a complex
    instruction set computer (CISC) architecture or a
    reduced instruction set computer (RISC)
    architecture
  • The difference between them is the number of
    clock cycles it takes to execute a single
    instruction
  • Some computer architectures require more cycles
    to execute the same instruction than others

50
Number of CPUs
  • Incorporating more than one microprocessor
    increases a computers processing power and speed
    because it can use more transistors and perform
    multitasking
  • Some computers have dual-core processors and
    quad-core processors
  • Besides multicore computers, multiprocessor
    computers are also available

51
Chip Set
  • The term chip set refers to a group of chips that
    support the microprocessor by controlling the
    flow of information between it and other
    components, such as the memory chips, graphics
    and sound cards, disk drives, and I/O devices
  • Various manufacturers produce different types of
    chip sets, which can significantly affect
    computer performance, due to the limitations that
    chip sets may impose on memory size, number of
    processors, and bus speed

52
Inside a Typical Computer
  • Some essential components of a modern computer
    include
  • The motherboard
  • DVD drive
  • Hard drive
  • Graphics card
  • Sound card
  • Network card
  • Ports
  • Power supply
  • Cooling system

53
Inside a Typical Computer (continued)
54
The Motherboard
  • The motherboard is a printed circuit board
    (PCB)a planar structure made of resin or other
    materials that contains the microprocessor and
    many other chips
  • It also includes the chip set and components that
    support the operation of a computer, such as
    capacitors and mechanical switches
  • A PCB supports and interconnects components
    through metallic traces called buses printed on
    the board

55
The Motherboard (continued)
  • Other components on the motherboard include
  • The BIOS chip
  • The chip set
  • Slots for connecting RAM modules to the
    microprocessor
  • Default circuitry for supporting sound and
    graphics capabilities
  • Expansion slots for connecting external graphics
    cards, sound cards, and network cards
  • Connectors for attaching hard drives, CD drives,
    and other disk drives to the motherboard
  • Ports for connecting I/O devices such as the
    keyboard and mouse

56
The Motherboard (continued)
  • Boards that carry the RAM chips are called memory
    modules, and are connected to the microprocessor
    through memory slots on the motherboard
  • Modern motherboards also come with extra memory
    slots to allow users to expand the RAM for faster
    processing

57
The Motherboard (continued)
  • Circuitry for supporting enhanced graphics may
    also be incorporated on separate PCBs called
    graphics cards or graphics adapters
  • These types of external graphics adapters connect
    to the motherboard via a special expansion slot,
    such as the AGP slot
  • Sound adapters enable a computer to output
    high-quality sound
  • Like graphics adapters, external sound adapters
    can be connected to the motherboard via one of
    its expansion slots, such as the PCI/PCI-E slots

58
The Motherboard (continued)
  • Computer networking is all around us, so
    motherboards also come with circuitry that
    supports networking
  • Alternatively, network adapter cards may be
    plugged into expansion slots on the motherboard
  • The motherboard also contains connectors and
    ports for hard drives, I/O devices such as the
    keyboard and mouse, and other devices

59
The Motherboard (continued)
60
Drives
  • Drives are devices that can read and write large
    amounts of information to and from various types
    of magnetic, optical, or electrical devices, such
    as hard disks, CDs, DVDs, and flash memory
  • If drives are installed in the computer case,
    they are called internal drives
  • If they are connected to the computer externally,
    they are called external drives
  • These drives attach to the motherboard using its
    specifically reserved connectors

61
Drives (continued)
  • One common type of hard drive is the Advanced
    Technology Attachment (ATA) drive, which is also
    called a parallel ATA drive, an Integrated Device
    Electronics (IDE) drive, or an Enhanced IDE
    (EIDE) drive
  • These drives include an integrated component
    called a controller, and are attached to the
    motherboard via special connectors
  • Other hard drives include serial ATA (SATA) and
    small computer system interface (SCSI) drives,
    which also attach to the motherboard via special
    connectors

62
Drives (continued)
  • SATA connections have two advantages over
    parallel ATA they can transfer data at a faster
    rate between the motherboard and the drive, and
    they are more physically compact
  • SCSI drives are faster than ATA drives, but
    because they are more complex, SCSI drives are
    not a standard feature of most computers
  • While internal hard drives connect to the
    motherboard with special connectors, external
    hard drives attach to the motherboard via
    Universal Serial Bus (USB) or FireWire ports
    outside the computer casing

63
Computer Ports
  • Peripheral devices may be connected to a computer
    through different types of ports that vary
    depending on the type of computer
  • These ports in turn connect to the motherboard
    itself
  • Some examples of ports include serial ports,
    parallel ports, video ports, S-video ports, USB
    ports, FireWire ports, sound ports, keyboard
    ports, mouse ports, network ports, and telephone
    ports

64
Computer Ports (continued)
65
Power Supply
  • A power supply is included within the computer
    casing (or externally) to convert the electricity
    levels from the wall outlet into levels that the
    computer can use
  • Besides power supplies, other components such as
    surge protection systems and uninterruptible
    power supplies (UPS) may be employed to safeguard
    the computer against sudden surges of electricity
    caused by lightning strikes, power outages, and
    other phenomena

66
Cooling System
  • A significant amount of heat is generated by the
    many electrical components in a computer, and
    problems can arise if these components are not
    sufficiently cooled
  • The chip that generates the most heat is
    typically the microprocessor
  • One popular technique to cool the chip is to
    install a metallic component called a heat sink
  • Another way to conduct heat away from the chip is
    to install a fan on the microprocessor or pass
    cryogenic materials or other liquids inside tubes
    in contact with the microprocessor

67
Cooling System (continued)
68
Types of Computers and Their Applications
  • Types of computers include
  • Desktop computers
  • Laptops
  • Handhelds
  • Mainframes
  • Supercomputers
  • Servers
  • Some of these computers may function standalone
    or as servers and clients
  • Some types of servers include e-mail servers,
    file servers, and Web servers

69
Types of Computers and Their Applications
(continued)
  • Servers usually have more than one processor,
    considerable memory, and extra hardware
  • One popular type of server is called a blade
    server
  • Blade servers can be controlled in a computer
    network through a remote access card installed in
    the server casing
  • They have the advantage of saving a significant
    amount of space they can be housed in remote
    locations such as data centers
  • These servers generate significant amounts of
    heat and must be kept properly cooled

70
Types of Computers and Their Applications
(continued)
  • Thin clients are computers that do not have the
    regular hardware typically found on other
    computers
  • They do not have a hard disk or other disk
    drives, and they have a scaled-down version of an
    operating system stored on a special memory chip
  • Thin clients rely on other computers over a
    network to perform most of their processing
    functions
  • Their major advantage is lower cost due to their
    lack of hardware and low power consumption

71
Types of Computers and Their Applications
(continued)
72
The Future of Computers
  • Although transistors have continued to shrink
    over the years in accordance with Moores Law,
    the trend will not hold true indefinitely
  • Similarly, wires that connect transistors to each
    other continue to diminish in size
  • This creates a problem as well, because very thin
    wires can cause a large loss of energy and limit
    the speed by which signals travel over the wires
    that constitute computer buses, thereby limiting
    the computers speed

73
The Future of Computers (continued)
  • Alternative technologies are underway, some of
    which include
  • Optical computing
  • Optical interconnects
  • Nanotechnology
  • Carbon nanotubes
  • Quantum computing
  • Biological computing

74
Storage Technologies
  • Storage technologies are critical for businesses
    to archive and access data, for governments to
    store important political information, and for
    libraries to store electronic information
  • Storage schemes initiated with paper punch cards
    and paper tapes
  • Magnetic tapes and disks were introduced later
  • Optical and electronic media were introduced last

75
Magnetic Storage
  • To record bits, a plastic tape, plastic disk, or
    ceramic disk is coated with a ferromagnetic
    materiala unique material that can be magnetized
  • The recording material is positioned close to a
    writing head that magnetizes small sections of
    the medium in one of two directions corresponding
    to ones and zeros
  • A hard disk stores information using the same
    principle as magnetic tape, but there are major
    differences in their recording formats

76
Magnetic Storage (continued)
77
Magnetic Storage (continued)
  • A hard disk stores bits on a circular disk (also
    called a platter) made of highly polished glass
    or another material
  • A typical computer hard disk has many of these
    circular disks stacked on top of each other
  • Each disk stores information on circular tracks
    and wedge-like sectors

78
Magnetic Storage (continued)
79
Magnetic Storage (continued)
  • In the case of magnetic tape, information is
    accessed serially (sequential access), whereas a
    magnetic disk can provide random access to data
  • Hard disks are limited mainly by their complex
    and sensitive mechanics for spinning, writing,
    and reading data
  • Floppy disks are external storage devices that
    are not widely used anymore except for file
    backups in some legacy systems
  • Floppies are conceptually similar to hard disks,
    but they have a much lower storage capacity

80
Optical Storage
  • Types of optical storage devices include
  • Compact disc-read only memory (CD-ROM)
  • Compact disc-recordable (CD-R)
  • Compact disc-rewritable (CD-RW)
  • Digital versatile disk-read only memory (DVD-ROM)
  • Digital versatile disk-recordable (DVD-R)
  • Digital versatile disk-rewritable (DVD-RW)

81
Optical Storage (continued)
  • Bits on optical disks are stored by creating
    small areas or domains with different reflective
    properties across a long spiral track
  • Bits are read by shining laser light on these
    tiny domains and detecting the light reflected
    back from them
  • Each domain reflects light in one of two ways,
    enabling the reader to distinguish between a one
    and a zero

82
Optical Storage (continued)
  • Bits on a CD-ROM are recorded by physically
    creating tiny protrusions, also called lands, on
    the CDs clear plastic surface during the
    manufacturing phase
  • Areas without lands remain shallow these areas
    are called pits

83
Optical Storage (continued)
84
Optical Storage (continued)
  • CDs can record many types of information
  • For a device to properly read and save the
    information stored on a CD, the device must use
    standard formats
  • For example, music on an audio CD is recorded
    following the Red Book standard developed by
    Philips and Sony
  • DVDs rely on the same principles as CD technology
  • DVDs can store much more data than CDs, primarily
    because the size of lands and pits can be
    diminished and spaced in closer proximity, and
    because more than one spiral track may be used to
    store data due to multiple layers

85
Electronic Storage
  • Electronic storage, also called semiconductor
    storage, has become an extremely effective
    technology for quick and efficient information
    storage
  • Electronic storage lets users save data quickly
    without the relatively lengthy burn process
    required for optical media such as CDs and DVDs
  • Electronic storage technologies store bits by
    trapping electricity within an array of
    transistors arranged on a silicon chip

86
Electronic Storage (continued)
87
Comparing Various Types of Storage Media
  • Hard disks provide very fast recording and access
    to information and can store large amounts of
    data
  • Because they can be written over and over again
    without encountering the limitations of CDs or
    DVDs, hard disks are currently the primary
    storage medium for computers
  • Optical disks are portable, lightweight, and can
    store information with greater stability than
    magnetic media
  • Optical disks are not affected by magnetic
    fields, so they are considered more robust than
    magnetic devices, which are prone to data loss
    over time
  • Electronic storage media are compact, fast, and
    versatile because they do not contain moving
    parts

88
Comparing Various Types of Storage Media
(continued)
  • Manufacturers can achieve greater capacity by
    reducing the physical area occupied by each bit
    on the media
  • However, each storage technology has a limit to
    its packing density
  • On magnetic media, the superparamagnetic effect
    causes random fluctuations toward the magnetic
    field if bits are packed too closely to each
    other
  • The ability to pack these bits closely on optical
    media is governed by the wavelength of light and
    the quality of the optics used to focus the laser
    beam onto the tracks

89
Comparing Various Types of Storage Media
(continued)
  • Integrated circuit fabrication technology limits
    the density of semiconductor storage devices
    because the size of transistors is limited
  • With advancements in chip manufacturing
    techniques, flash memory devices are now
    considered to be at the forefront of portable
    storage technology
  • The ultimate limitations of all these storage
    technologies have spurred a large amount of
    research for alternatives, including holographic
    storage and molecular storage

90
Summary
  • Transistors can be combined to create logic
    gates, which can be used as the basic building
    blocks for integrated circuits
  • A computers fundamental components include
    input/output (I/O) devices, a central processing
    unit, main memory, storage (secondary memory),
    and an interconnection system
  • Factors that affect the performance of computers
    include word length, bus width and bus speed,
    memory size and memory access speed, processor
    rate, instruction set, number of processors, and
    chip set

91
Summary (continued)
  • Components you can expect to find in a modern
    computer include the motherboard, CD drive, hard
    drive, graphics adapter, sound adapter, network
    adapter, ports, power supply, and a cooling
    system
  • Computers come in various types, including
    desktop computers, laptops, handhelds,
    mainframes, supercomputers, servers, and thin
    clients
  • Future possibilities for computing include
    nanotechnology, quantum computing, and biological
    computing

92
Summary (continued)
  • Magnetic media store digital data by magnetizing
    a ferromagnetic medium in one of two directions
  • Optical media store digital data by creating
    domains with different reflectivities
  • Electronic storage media save data by storing
    different levels of electrical charge through
    transistors
  • Magnetic tapes are classified as serial access
    devices hard disks, floppy disks, CDs, DVDs, and
    electronic memory are classified as random access
    devices
  • Possible alternatives for future storage media
    include holographic and molecular storage
Write a Comment
User Comments (0)
About PowerShow.com